I'm not too worried about moisture. The car was relatively dry to begin with, the only rust issue was small pin holes in the pass floorboard and that was replaced with new metal. It stays in the garage and doesn't see much moisture, I have only driven it twice in the rain. Black cars are a *****!
The guy that did the work isn't going anywhere. If I couple of years down the road I start having problems, I know where he lives.